Sometimes the PVB's do that. I would turn the water off at the first ball valve on the Backflow, then shake the backflow a little, and tap the top. Then shut the other valve (both off) and quickly open the first valve until it seals (go back and forth) once it seals you ca slowly open the other. If this works fine! If you had the system installed call your contractor. If not you may need to visit an irrigation dealer for help!
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers